The soybean cyst nematode (SCN) has been managed for decades with resistant soybean varieties. Almost all soybean varieties have SCN resistance from a breeding line named PI 88788, and SCN populations have developed high levels of reproduction on the PI 88788 resistance. The results of a field experiment in southeast Iowa in 2019 foreshadow alarming yield loss due to SCN in the future if farmers continue to have only PI 88788 SCN resistance available in soybean varieties.
Integrated Crop Management News
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Choosing corn hybrids and soybean varieties is one of the most important crop management decisions to be made. It is a hard decision to make because it is typically made months before the growing season begins. This article will explore where to find yield trial information, how to interpret yield trials, and what to consider in selecting cultivars.
Continuous corn is a "three strikes and you’re out" situation. And the first strike is automatic – high residue volume. This is how a farmer recently described it to me.
Making continuous corn work means knowing what you are up against. First, realize that the yield drag for continuous corn can range from 0% to 30% but is typically between 5% and 15%. Yield drag has been associated with cooler and wetter soils, nitrogen (N) immobilization, increased disease risk, and allelopathy – all of which are influenced by corn residue volume.
Resistant varieties continue to be a key tool for managing the soybean cyst nematode (SCN). With financial support from the soybean checkoff through the Iowa Soybean Association, Iowa State University annually compiles a list of SCN-resistant soybean varieties that are available for use in Iowa.
The updated list of maturity group 0, I, II and III varieties is now available for free online in the Iowa State University Extension Store.
Crop residue serves an important role in physically protecting soil from erosion during rain events or high winds, as well as enhancing the soil biological activity by providing sources of organic carbon and nitrogen for its energy needs. In order to understand how residue decomposes, we need to understand how the degradation processes are influenced by environmental and soil conditions; namely, air and soil temperatures, soil moisture availability, soil pH, oxygen, and type of microbial community.
A critically important fall activity that can pay large dividends for next year’s soybean crop is sampling fields for the soybean cyst nematode (SCN). Also, some farmers might consider sampling fields in which soybeans were grown in 2019 if disappointing yields occurred for no apparent reason. This article discusses how to collect a meaningful SCN soil sample, where to send the sample to get it processed, and how to interpret SCN soil sample results from Iowa State University.
Fall nitrogen (N) fertilizer application continues to be popular for several reasons, including lower cost, time for application, equipment availability, often better soil conditions, and competing springtime field activities.
This year continues the chain of growing seasons with extremes and rapid changes beyond our long-term experiences. This made for periods of both stress and favorable crop growth despite the planting dates. Frost, potentially killing in the northern half of Iowa, is expected between October 11-13. USDA data indicate a wide range of maturity due to planting date, but the periods of hot weather scattered through September and early October may have reduced the potential for very high moisture corn and soybean. Variability will be the key issue to manage in 2019 corn and soybeans.
Very variable weather this season will result in variable corn and soybean yield within and between fields. Entire fields or portions of fields were planted later than usual or were not planted. This will result in variable removal of phosphorus (P) and potassium (K) with harvest. Reduced yields combined with continued low market values create uncertainty about P and K fertilization decisions for the 2020 season.
The plentiful rain in September has provided ideal conditions for establishment of winter annual weeds, thus many no-till fields will have dense stands of these weeds going into winter (Fig. 1). The wetter springs we have encountered recently complicate getting spring burndown applications made in a timely matter.